Furnace hearth



June 14, 1960 a. K. WALPOLE FURNACE HEARTH 3 Sheets-Sheet 1 Filed March26, 1956 Beverfy/f- INVENTOR. 6400/8 BY ATTORNEYS.

June 14, 1960 B. K. WALPOLE 2,940,743

FURNACE l-IEARTH Filed March 26, 1956 3 Sheets-Sheet 2 on mmvroa eve/{yif. ZVb/j o/e A TTORNEYS June 14, 1960 Filed March 26, 1956 B. K.WALPOLE FURNACE HEARTH 3 Sheets- Sheet s IN V EN TOR. Be ve/{y K VVr/floAT TO RNEYS.

United States Patent FURNACE HEARTH Beverly K. Walpole, Cranston, R.I.,assignor to National Furnace Corporation, a corporation of Rhode IslandFiled Mar. 26, 1956, Ser. No. 574,028

4 Claims. Cl. 263-21) This invention relates to improvements in a hearthfor a furnace employed for heat treating material, particularly a hearthfor a furnace of the continuous operation type in which the work is fedin at one end, advanced through the furnace, and discharged from theother end.

In furnaces of the above type the work is loaded on the hearth at oneend thereof, and by vibrating the hearth or advancing and suddenlystopping the hearth, the work is made to move to the other end thereof.The furnace is operated in a continuous manner, and the work is loadedon a platform joining the hearth, or a continuation of the hearth. Thework is moved along the platform on to the hearth and as it enters thefurnace is relatively cold. This causes large heat differentials of thehearth for a substantial distance within the furnace causing greatthermal shocks and contraction and expansion of the hearth, whichresults in conditions causing the hearth to have a relatively shortlife.

, Hearths of the above character are usually a one-piece structure, andthe surface along which the work is moved must be maintained smooth andfree of obstructions to the movement of the work. The hearths arerelatively thick and heavy, and when it becomes necessary towithdraw'the same from the furnace for repair, as by way of example, tofree the surface of work particles which are more or less weldedthereto, considerable time is spent in waiting for the hearth to cool topermit working thereon and likewise waiting for the furnace to cool soto return and mount the hearth within the furnace, and much labor isinvolved pulling the hearth out of the furnace. A. hearth of the lengthrequired being subjected to dift'erent temperatures cannot expand evenlyand thus becomes buckled along portions thereof where the widely varyingtemperatures occur.

, object of the invention is to improve generally on hearths forfurnaces of the above character.

Another object of the invention is to provide a hearth so constructed asto be readily removed from the furnace.

Another object of the invention is to provide a hearth constructed ofsections so as to permit easy removal and replacement of a damaged partthereof.

Another object of the invention is to provide a hearth so constructed asto be supported and actuated on the existing hearth of a furnace.

A more specific object of the invention is to provide ahearth havingwork engaging surfaces composed of shortreplaceable units, eachindependently expandable without exerting strain on other units of thehearth.

Another object of the invention is to provide my hearth over thatusually employed, causing it to be a sub-hearth of my improved furnace.

With these and other objects in view, the invention consists of certainnovel features of construction as will be more fully described andparticularly pointed out in the appended claims.

In the accompanying drawings:

Figure l is a plan view of my improved hearth shown connected to aportion of a hearth vibrating mechanism;

Figure 2 is a plan view of the frame of the hearth;

Figure 3 is a longitudinal sectional view of a fragmentary portion ofthe frame of Figure 2 taken substantially along line 33 of Figure 2 andshown on a larger scale;

Figure 4 is a sectional view taken substantially along line 4-4 ofFigure 3;

Figure 5 is a sectional view taken along line 5-5 of Figure l shownona'larger scale and showing the subhearth and the support for the hearthwhich was omitted in Figure 1 Figure 6 is a lateral sectional view takenalong line 6-6 of Figure 5 but with the roller mechanism shown in Figure5 omitted;

Figure 7 isa plan view of the sub-hearth omitted from Figure 1; Y a tFigure 8 is an elevational view of the sub-hearth shown in Figure 7;

Figure 9 is a plan view of a single unit of the hearth; and

Figure 10 is a sectional view of a portion of a hearth unit takensubstantially along line 1i 10 of Figure 9.

The hearth 14 (Figure 1) according to the embodiment illustratedcomprises an open frame 15 (see Figure 2) having sides 16 which are madeof cylindrical stock and secured to each other by a plurality of equallyspaced cross members 17 which are also cylindrical in crosssection. Themembers 17 are similar, and the end portions are turned at right anglesas at 18 and extend along the inner surface of sides 16 and are therewelded in place. A second cross member 19 is positioned adjacent eachmember 17 in spaced relation therewith. The member 19 is made of flatmaterial generally rectangular in cross section, and the ends abutagainst the sides 16 and there Welded in place. These cross members 19are of a width equal to the diameter of the sides 16 and are relatedthereto to extend across-from one side 16 to the other side 16tangentiallyto the top and bottom thereof.

The frame is additionally reinforced by longitudinal members 20 whichextend from a cross member 17to a cross member 19. As best seen Figure3', each mem; ber 20 is made 'of flat stock and extends edgewise withthe ends thereof abutting against cross members 17 and 19 andtherewelded in position. The member 2% extends frommember 19 at a slightangle upwardlyfrom the plane of the frame, as seen in Figure 3, and istapered, as at 21, forming an edge support 22 which is slightly inclinedto a plane extending tangentially from the sides 16. There are two rowsof these members or stringers 26 spaced from the sides, as seen inFigure 3, with each member 20 in a row extending lengthwise of theframe.

[The portion of the frame so far described, which extends to the left ofthe cross member 17' and including this member T7, is made of a highheat resistance material known in the art, as by way of example, highnickel chrome alloy steel. This portion of the frame 15 is adapted to beposition'ed Within the furnace (not shown).

The portion to the right of cross member 17' does not enter the furnace,and for the sake of economy of manufacture, the portion of the framewhich extends to the right of the cross member 17 and which includes thesides 16, cross member 17", and longitudinal members 29' is made of asteel less resistant to heat and thus less expensive. The sides 16 aresecured to the sides 16 as. at 23 by means of a weld joint. The freeends of the sides 16 are provided with screw threads 24 for a purposewhich will hereinafter appear. a

The work holding surface or floor 14 of the hearth comprises a pluralityof separate units 3! which are laid along the frame 15 with the adjacentend portions of the units overlapping each other in the manner ofshingles. Each unit 30 extending to the left of cross Patented June 14,1%69 t In order to ass'ure the position of units 30 in n'ested as tofree the damagedunit." a i I a a j The hearth 14 above described maylbemade part of t anyof various hardening-furnaces to which the hearth t VV t t emember 17 is similar to the other and comprises a sheet 'met'altray-like body (see Figure 9) having a floor 31 and 'side flanges 32which extend at'substantiallyright angles to thefloor 31,} One end ofthe tray is prov ded with a lip 33 which is ofless width than-the floor3;, as showng The lip 353; extends downwardly at an acute angle to thevertical with the endtportion 33' the'reof turned outwardly atsubstantially 90 and thus forms an L-shaped pr'ojection orhhookdepending from the floor 31 at the t 7 rear end thereof; The unit 30 ismade wider at the rear and tapered to the forward end for a purposewhich will hereinafter appear. 1 p I V V V t V As. best seeniin FiguresS and each umt' 30 1s det tachahly secured to the frame by passing :thelip 33 m the a e b we adi a s t memb 19; a deta mp4s engaging the frameat spaced intervals so that a'minimum "of ,heatfiis transmitted to thesubrhearth. The rear or v right end of the sub-hearth'ej, as seen inFigure 8, has 1 a depending flange 39 which provides for connect ng theing the turned end portionqthereof beneath the member 1'7; Aspreviouslyjdescrihedi the um'ts '30 are madewider at the rearendQthereof and so dimension ed that the forwardtend of each unit 30will be received in nested relai tion'within the rear end of an adjacent,unit and inoverlapping relation therewith in a shingle-like fashion;Thus,',

the weight, of each unit in addi-tionto the weightof the workservesttore'tain each unit in place. a It will be seen in these twoFigures Sand 6 that the floor 31 of each unit 30 rests at some] point onthe side members 16.

' It will also be seenthatjthe said floor 'rests'on the edges 220f 'thelongitudinal stringers'zfl, whichedges extend '7 against an abutment tostop-the hearth with a'suddeii r ofinertia to move the work relativelythe floor of the hearthfrom -the-location of "cross mem: 4

' V 'ber 17" to the discharge end of theh earthl 30 I is similar to unit30 with, the egiceptionlthat itl isfmad e'g longer' and extends-fromtliecross nieniber17"'to overlap V the'unit 30 which is'hooked to thecross 'membier 1 7. ,The unit or pan 3%: likewise rests onllongitudinalmemib'ersmr stringers V 20""whichiare similar to stringer '20 7with "the exception that these steell'essresistant to heat. 1'

F er re ma e Q 'a relation, each unit tat vthe overiapping end-isprovided withan opening 34 (see Figure 5)"tth'rough the flanges SZth'ereo f. The opening i Qnefian ge will be positioned I inregistertwithan opening in th'e' a djacentflange, as "pin or thelike 35is insertedin the s'aid.registered'open- "ing and is welded to the outerof said flanges as at a 36 (see Figure 5). 'ihe pin'js made flush withthe inner V 'side'of the inner flange SZ-soja ltd-eliminate any obstruc'e V A tion to the smooth flow of work along the hearth. Wheh f itbecomes necessary toj'replace a damaged unit 3 0, the

pin 35 may be removed by applying a hammer 'or like may be adapted. Itis, however, one aspect of the present invention to use the'hearth 14with furnaces' of the above type and to employ the existinghearththereof for t a snpport'for the hearth 14 and to modify thefvibratingmechanism thereof ina manner to adapt the 'same for sub-hearth to a workloading table or platform 40 which has side flanges '41. The flanges 41are continued to depend below the floor. 42 and provide tracks 43. A

' flange 44 depends from the floor 42 against which the flanges 38 abut.Bolts 45 'erttend through flanges 3 8 and 44 which secure the sub-hearth37 to the platforlufiot' The sub-hearth 37 proper is mounted on freerollers 46 (see Figured) which extend laterally beneaththe subhearthS'I-Tand are held captiveinl'bearings 47 which are attached to the brickbed 4.8toftthe furnace. Thus, the

sub-hearth 37 is mounted for reciprocating motion; that is, thesub-hearth maybe moved longitudinally thereof first in one'direction andthen in the other. The plate form is likewise mounted torreciprocatingmotion 'by means ofrollers 49 (see Figurel') onwhich the tracks 43 rest.The rollers are mounted on shafts jo which are journaled in pillowblocks 51 securedton'the frameof a hearth vibrating mechanism indicatedgenerally/52. The 'elementst'of the vibrating n'iechanism are not shown,in that the specific type of vibrating mechanism is not the lsubject ofthe present invention, itbeingunderstood that the mechanism indicatedgenerally 52 is iintendedito be representative of any suitable typewhich operates it) move the hearth and sub-hearth in the forwarddirection 'jerk followed by a return to standing position for are;peated operation response to the well-tknown'princip'le hearth. V V a at In order to adapt the existing mechanism of the furnace .for'usewithithehearth 'of the present invention; a sup port 53 in the form of'acrossbar is secured to the right end edge portion at the'platfofmvifl;'aridfthis stipport 53 is slotted inwardly from 'the uppei' edgeas Thethreaded end portions' 2 4 are received in said slots 53 and secured tosaid support byclampnufs: 55. The frame 15 lies on the floor 42 ofthe-platform and on the sub-hearth37 which now becomesja supportp forhearth 14. The free'endportiofi'of the frame 1 5a provided with lugs 56(see Figures}, 4, and eywhieh are in the form of short cylindersattached to the sides 16 at alocation to engagealong the walls 38' ofthe outer trough siof the sub he'arth 37 Thus, the lugs 56 and thesecuring means at'the-forwa'rd end of the frame prevent L lateralshifting of'the hearth 14 on the sub-hearth 37; "It

will be apparent that vibrating motion imparted to the; platform40'will: be transmitted to the sub-helarth-S-lhrid hearth 14." t t Llt'will betapparent' froni the above descriptiori that-the structure ofthe 1163111114 provides'for a relatively-light 'Weight hearth whichlends itself to' be readily handled when necessary for'repair orreplacement era unit' 30.'

V V 'Allflthat is necessary :in order to pull thehearth from the blowtothe inner side of the pin to remove the samefs'o furnace isto loosenitheclamp nuts sufliciently to permit removal of the fram e jportions24fromfthe notches 7 I54. This trailingend of the hearth may be nowraised 60' t to a height to position beneath-this raised end someimprovised support, as for example a bar or roller; Then by the use of apair of tongs and/or the 1ike,fthehearth vibrating' the hearth 14.1 ln'Figures w7 andS 'Ith ave illus-f j trated' a't '37tthat which forrnerly'was the hearth in com In rno'n ne in furnaces of the above'type whichthe 7 i worir ist advanced by lmown haechnistnit'l'his former he th w hr i s hearthlfi' 'd i a enerall w fie tangular plate whieh 'is'corrugated or undulated tin cr oss section -'(see' Figure :6) aproviding. longitudinal m sh' i fie t in @21 n d fiih be fb hen he aud ml lli k t it pe aa ed mesa? I may be slid along'the said.improvised supportrelative to the sub-hearth and withdrawn from -th'egfurnace afdis tancesufiicient to exposeithe unit to' be replaced. The

' construction permits a'r'elativelywquick cooling of, the

exposed units and by detaching the unit to be replaced t as f previouslydescribed and'replacing the same with'a nother;unit',fthe hearth may be"returned in position by merely pushing the frame and units 30 in placeand then turning the clamping, nuts to secure jthehearth to the platform49, all this without disturbing the sub-heanh 37 from its mounting.

1 claim:

; tl.;1n1a furnacefor heath-eating materialhavingopen ings for thecontinuous passage of material therethrough, a substantially horizontalhearth comprising a frame having pairs of crossbars, a plurality ofplates having fixed and free ends with their free ends overlapping thefixed ends of the next plate in shingle like fashion to permit freelongitudinal expansion thereof, each plate provided with a generallyZ-shape lip at its fixed ends extending over one of the pair of bars andbeneath the other of said pair of bars and which may be moved to andfrom secured position only with the free end of the plate lifted awayfrom the frame a substantial distance.

2. A furnace according to claim 1 wherein said plurality of pairs ofcross bars are spaced from each other a distance less than the length ofone of said plates.

3. A furnace according ot claim 1 and longitudinally extending stringermembers extending between said cross bars in the space between saidpairs of cross bars and on which said platas rest.

4. In a furnace for heat treating material having openings for thecontinuous passage of material therethrough, a substantially horizontalhearth comprising a frame having crossbars, a plurality of plates, meansindividually securing one end of each of said plates to said frame withthe other end free and overlapping the secured end of the next plate inshingle like fashion to permit free 1011- gitudinal expansion thereof,said securing means including lips on said plates extending to alocation vertically beneath said crossbars, whereby said secured end islocked against being lifted in a direction substantially vertically fromsaid frame and a sub-hearth of undulating form having crests and valleyspositioned below the said first hearth with the crest engaging the firsthearth at a multiplicity of spaced locations distributed over the entirearea of the frame for movement therewith.

References Cited in the file of this patent UNITED STATES PATENTS660,982 Clary et al. Oct. 30, 1900 1,564,813 Babendreier Dec. 8, 19252,041,811 Betterton et al May 26, 1936 2,041,844 Linder May 26, 19362,666,995 Kirkpatrick J an. 26, 1954 2,779,470 Walters Jan. 29, 1957

